1. Field of the Invention
The present invention relates to novel polysaccharides, their preparation and therapeutic compositions containing them.
More particularly, it is concerned with polysaccharides that are obtained by purifying hot-water extracts of the bark of Melia azadirachta L. their preparation and therapeutic compositions containing them. The polysaccharides of the invention are useful for the therapy of a variety of cancers.
2. Description of the Prior Art
It is heretofore known that extracts from Melia azadirachta L. show various pharmacological activities. In fact, there are disclosed a method of producing cosmetics for the skin from the bark, leaves, flowers, fruits, root epidermis or resin of Melia azadirachta L. by extracting the same with water or a hydrophilic solvent or by finely pulverizing the same (Japanese Patent Publication Nos. 28853/77, 28854/77 and 10125/78); a method of preparing from such raw materials from Melia azadirachta L., constituents possessing antimicrobial activities or gastrointestinal or hepatic function-improving activities by extracting the same with hot water (Japanese Patent Publication No. 10124/78); and a method of preparing from such raw materials from Melia azadirachta L., constituents effective for the therapy of dermatological and rheumatic diseases by extracting the same with a hydrophobic solvent (Japanese Patent Publication No. 13689/78).
After extensive studies on the pharmacologically active constituents of the bark of Melia azadirachta L., we have isolated polysaccharides having anti-tumor activities from hot-water extracts of the bark. It has not been disclosed in the prior arts that the bark of Melia azadirachta L. contains polysaccharides.